When I check my email this morning, I was surprised to find 64 emails sitting there wanting attention. I was more surprised to find that most of these were 'delivery failure' notices, all from emails which I hadn't sent. Even more surprising was that these were all send during a brief time window between 21:51 and 21:59.
I hope nobody out there is receiving junk email from this domain, but I can assure everyone that I'm not sending any out myself. This is most likely due to spammers inserting my domain as the 'from' address. Some information about the problem can be found here.